1. Field of the Invention
The present invention relates to sound absorbing structure of electronic equipment having the structure for cooling a heat generating element by means of a blower.
2. Description of Related Art
It is common knowledge that the development of a semiconductor used for electronic equipment, especially of a semiconductor as typified by a CPU of information processing equipment is remarkable, and the semiconductor heads for high heat generating amount and high density. In this connection, due to increase of the mounting number of blowers for cooling and the revolution speed of the blower, the noise value of the equipment also tends to increase. On the other hand, the frequency of placing the electronic equipment in an office room increases, and therefore the demand of decreasing noise of the electronic equipment becomes strong. Accordingly, sound absorbing structure using an acoustic material is often disposed in the vicinity of the blower in an electronic equipment case, or in a rack cabinet and the like outside the electronic equipment case where the electronic equipment is installed. In the case of the conventional sound absorbing structure providing a sound absorbing channel by combining a plurality of acoustic materials as shown in FIG. 10, the volume of the sound absorbing structure per se becomes large, and therefore there have been many restrictions on an installation space, handling, and the like. Further, due to its imbalanced sound absorbing structure in which the plurality of acoustic materials are combined, the distribution of cooling fluid becomes uneven, which may be an obstacle to uniform cooling of the inside of the electronic equipment. In addition, while the recent electronic equipment basically has the same substrate and sheet metal structure in its inside, it becomes often the case that the equipment is used across several generations by replacing a CPU mounted in its inside. Therefore, the revolution speed of the blower has been changed in order to obtain the cooling capability adequate to each generation, and the sound absorbing structure has been changed in response to allowable fluid resistance of the internal equipment.
The conventional sound absorbing structure is also shown in JP-A-5-226864, JP-U-3-48293 and JP-U-63-145392, for example.